Type printing apparatus



J. HANDLEY June 12, 1962 TYPE PRINTING APPARATUS 2 Sheets-Sheet 1 Filed Jan. 9, 1961 Inventor J'- HANDLEY By W Attorey J. HANDLEY June 12, 1962 TYPE PRINTING APPARATUS 2 Sheets-Sheet 2 Filed Jan. 9. 1961 Unite 3,h38,58il Patented June 12, 1962 3,038,580 TYPE PRINTING APPARA'IU5 John Handley, Little Mai-land, Briar Hill, Parley, England Filed Jan. 9, 1961, er. No. 81,613 Claims priority, application Great Britain Ian. 9, 1960 4 Claims. (Cl. 19782) This invention relates to improvements in or relating to type printing apparatus.

It is one of the objects of the present invention to provide improved type printing apparatus in which the effective mass of a carriage and type printing head accommodated thereon is reduced by urging the carriage in a letter-feed direction other than by well-known leadscrew means and using such lead-screw means only to permit step-by-step movement of the carriage while it is being urged thereof in the letter-feed direction, and to drive the carriage in a direction reverse to the letterfeed direction.

According to one aspect of the present invention, type printing apparatus is provided including a type printing head mounted on a carriage, a lead-screw engaged by said carriage, means for urging said carriage in a letter-feed direction independently of said lead-screw, and means co-acting with said lead-screw to effect step-bystep movement of the carriage while it is being urged by said urging means in the letter-feed direction.

According to another aspect of the present invention, type printing apparatus is provided comprising a type printing head mounted on a carriage, means for urging the said carriage in a letter-feed direction, a lead-screw engaged by said carriage, means for driving said leadscrew independently of said carriage, spring means interposed between said urging means and said driving means for balancing the urging and driving forces applied to said carriage and lead-screw, ratchet and pawl means coacting with said lead-screw for arresting and releasing rotation of the said lead-screw to affect starting and stopping of said carriage while it is being urged by said urging means in the letter-feed direction, and spring means incorporated in said urging means to accelerate movement of the carriage after a stoppage.

The invention will be better understood from the following description read in conjunction with the accompanying drawings in which:

FIG. l is a part sectional plan view of the apparatus;

FIG. 2 is a part sectional side view of the apparatus; and

FIG. 3 is a part sectional end view of the apparatus.

Referring now to the accompanying drawings and in the first instance to FIG. 1, the means for driving the type printing head 1 mounted on a carriage 14 in the letter-feed and carriage-return directions, and relative to a printing platen 13, comprises a shaft 2 continuously driven by electro-motor means (not shown) in the direction indicated by the arrow C. Two gears 3 and 5 are pinned to the shaft 2 of which gear 3 drives gear 4, and of which gear 5 drives gear 6 by way of an idler gear '7. Gears 4- and 6 are free to rotate on a clutch shaft 8 and are affixed respectively to portions 9 and 11) of separate magnetic clutches, the other respective portions 11 and 12 of which clutches are affixed to the clutch shaft 8. With the clutch constituted by portions 9 and 11 energised, a magnetic coupling exists between these portions, so that clutch shaft 8 is driven in a clockwise direction, as viewed from the bottom of FIG. 1. Gear 6 is caused to free-wheel through de-energisation of the clutch associated therewith and which clutch is constituted by portions and 12. In this condition of rotation of shaft 8 the printing head 1 is driven in the carriage-return direction by means later to be described. With the clutch constituted by portions 10 and 12 energised, a magnetic coupling exists between these portions, so that clutch shaft 8 is driven in an anti-clockwise direction. Gear 9 is caused to free-wheel through de-energisation of the clutch associated therewith and which clutch is constituted by portions 9 and 11. In this condition of rotation of shaft 8, the printing head 1 is driven in a letter-feed direction by means to be described later. It is so arranged that only one clutch is energised at a a time.

The means for urging the carriage 14 and the type printing head 1 in the letter-feed direction indicated by the arrow A is constituted by a cable drum 15 which is afiixed to shaft 8 and incorporates, extending from a side thereof, two tongues 16 (FIG. 3) which are disposed apart. FIG. 3 also shows in section two pairs of tongues 17 which extend from the side of the bevel gear 18 of FIG. 1 which bevel gear is accommodated on clutch shaft 8 and rotatable with respect thereto. Bevel gear 18 and bevel gear 21 affixed to the lead-screw 22 constitute the means for driving the lead-screw 22. Each tongue 16 of the cable drum 15 is disposed between a pair of tongues 17 of the bevel gear 18 and separated from the tongues of a pair by a resilient buffer 19 on one side and a compression spring 20 on the other side. A ratchet wheel 23 is affixed to the lead-screw 22 and is arranged to be engaged by a pawl 24.

The carriage 14 and the type printing head I mounted thereon are arranged for movement in the carriage-return direction, indicated by the arrow B, though the provision of a nut portion 25 affixed to the carriage 14 and engaging the lead-screw 22. Extending members 26 of the carriage 14 are drilled to accommodate therethrough a rod 27 having a crotch portion 28 extending from one end, which crotch portion accommodates the knuckle end 29 of a cable 30 and which knuckle is pivotally attached to the crotch portion by a pin 31 extending through both items. The other end of cable 30 is affixed to the cable drum 15 in the position shown in FIG. 2, so as to be wound up thereon or withdrawn therefrom. A spring 32 is accommodated on rod 27 between the extending members 26 of the printing head 1 as are adjusting nuts 33.

Operation of the apparatus is now to be described and firstly with reference to FIG. 1. Initially the pawl 24 is in engagement with the ratch wheel 23 on lead-screw 22, thus rotation of the lead-screw 22 and movement of printing head 1 is prevented. When shaft 2 is rotated to drive clutch shaft 8 in an anti-clockwise direction, via gears 5 and '6 and idler gear 7 therebetween and the energised clutch constituted by portions 10 and 12 thereof, the cable drum 15 commences to wind on cable 30 and causes spring 32 on rod 27 to be compressed between adjusting nuts 33 and the right-hand extending member 26 of the carriage 14. At the same time springs 20 (FIG. 3), between tongues 16 of cable drum 15 and tongues of pairs of tongues 17 of bevel gear 18, are being compressed, since bevel gear 21 on lead-screw 22 is held stationary through engagement of pawl 24 with ratchet-wheel 23 on the leadscrew. When the pawl 24 is disengaged from ratchet wheel 23, the compressed springs 20 accelerate the leadscrew 22 and the compressed spring 32 accelerates carriage 14 and the printing head I mounted thereon through a step in the letter-feed direction, indicated by the arrow A, and relieves the load of the carriage on the leadscrew. This step is terminated when the pawl 24 reengages with a tooth of the ratchet Wheel 23 to bring the carriage and printing head to rest. It will be readily understood that the force applied to urge the carriage 14 and type printing head I mounted thereon and the force applied to drive the lead-screw are balanced by the spring 20 disposed between the drum 15 and the bevel gear 18. Each time the pawl 24, which may be of the type described in British Patent No. 808,703, is disengaged from the ratchet wheel 23 it is advanced to reengage a succeeding tooth in the ratchet-wheel 23.

During each step-by-step movement of the carriage 14, the effect of backlash between the nut 25 thereon and the lead-screw 22 is nullified, since it is always taken up by spring 32 which is being compressed prior to each step of the printing head 1 through the pull of cable 30.

This step-by-step movement of the printing head 1 is repeated until the end of the line of print is completed, termination of the movement being eifected by the disengagement of the clutch constituted by portions and 12 thereof. The clutch constituted by portions 9 and 11 thereof is thereafter energised, and clutch shaft 8 is rotated by shaft 2, via gears 3 and 4, in a clockwise. direction. In consequence the compressive forces exerted on spring 32 and springs 20 are released, nuts 33 move back into engagement with the left hand extending member 26 of the carriage 14, and tongues 16 on cable drum 15 move back against resilient buffers 19 between the tongues 16 and one of each pair of tongues 17 on bevel gear 18. The lead-screw 22 is then driven by bevel gears 18 and 21 to move the carriage 14 and type printing head 1 thereon in the carriage-return direction, indicated by the arrow B, in preparation for the commencement of a new line of print.

It will be readily understood therefore that during stepby-step operation of the apparatus, the following advantages accrue: the load on the nut 25 is relieved; the mass to be moved is reduced, since a pull independent of the lead-screw 22 is exerted on the carriage; the backlash between nut 25 and lead-screw 22 is taken up continuously during movement; and the frictional forces set-up between the nut 25 and lead-screw 22 and guide means (not shown) are utilised for retarding the printing head 1 during arrestment of the movement thereof through the engagement of pawl 24 with ratchet wheel 23.

It is to be understood that the foregoing description of specific examples of this invention is not to be considered as a limitation of its scope.

What we claim is:

1. Type printing apparatus comprising a type printing head mounted on a carriage, means for urging the said carriage in a letter-feed direction, a lead-screw engaged by said carriage, means for driving said lead-screw independently of said carriage, spring means interposed between said urging means and said driving means for balancing the urging and driving forces applied to said carriage and lead-screw, ratchet and pawl means coacting with said lead-screw for arresting and releasing rotation of the said lead-screw to effect starting and stopping of said carriage in the said urgency thereof in the letter-feed direction, and spring means incorporated in said said urging means to accelerate movement of the carriage after a stoppage.

2. Type printing apparatus including a type printing head mounted on a carriage, a leadrscrew engaged by said carriage, means for urging said carriage in a letterfeed direction independently of said lead-screw, means for driving said lead-screw independently of said urging means, means co-acting with said lead-screw to effect step-by-step movement of the carriage while said carriage is being urged in the letter-feed direction, clutch means for applying driving forces to said urging means and to said means for driving said leadscrew so as to move said carriage in a letter-feed direction, and spring means interposed between said urging means and driving means to balance said forces applied thereto.

3. Type printing apparatus, as claimed in claim 2 in which second clutch means is provided to apply a force to said lead-screw to drive said carriage in a direction reverse to said letter-feed direction.

4. Type printing apparatus including a type printing head mounted on a carriage, a lead-screw engaged by said carriage for controlling the movement thereof, releasable means for holding said lead-screw against rotation, drive means, first spring means connecting said drive means with said lead-screw for rotation of said lead-screw when said holding means is released to cause movement of sair carriage in a letter-feed direction, and second spring means connecting said carriage with said drive means for urging said carriage in a letter-feed direction independently of said lead-screw, whereby when said holding means in released, said first spring means accelerates the rotation of said lead-screw and said second spring means aids in accelerating the movement of said carriage.

References Cited in the file of this patent UNITED STATES PATENTS 559,325 Ellis Apr. 28, 1896 635,957 Fairfield et al. Oct. 31, 1899 2,606,641 Kleinschmidt Aug. 12, 1952 

